Electron Beam Surface Potential Measurement
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Solution Overview
Problem
Conventional electron beam inspection methods struggle to precisely measure the surface potential of semiconductor devices with insulating films, as the primary electron beam irradiation redistributes electric charge, leading to inaccurate measurements and decreased resolution due to complex energy filter constructions.
Innovation Solution
Optimizing the primary electron beam energy to suppress secondary particle yield to 1, allowing for precise surface potential measurement without complex equipment like energy filters, by observing S curves and using a control electrode to calculate surface potential from secondary particle signal strength.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional electron beam inspection methods are used to measure surface potential, then measurement can be performed, but measurement precision deteriorates due to charge redistribution by primary electron beam irradiation
Solution Approach 1:
The patent changes the energy parameter of the primary electron beam, specifically optimizing it to 5 keV or lower. This parameter change suppresses secondary particle emission and prevents charge redistribution on the insulating film surface, thereby maintaining measurement precision and reliability simultaneously
2Measurement precision
If energy filters are used to measure surface potential, then measurement capability is improved, but device complexity increases due to complex construction
Solution Approach 1:
The patent extracts and removes the complex energy filter construction from the measurement system. By optimizing the primary electron beam energy to 5 keV or lower, the patent achieves surface potential measurement capability without requiring energy filters, thereby simplifying the device construction while maintaining measurement precision
3Difficulty of detecting and measuring
If primary electron beam irradiation is used to obtain secondary electrons, then signal detection is enabled, but manufacturing precision deteriorates due to charge redistribution on insulating films
Solution Approach 1:
The patent changes the energy parameter of the primary electron beam to 5 keV or lower. This parameter change creates an optimal balance where secondary particle emission is suppressed enough to prevent charge redistribution on insulating films, yet sufficient signal is still obtained for accurate surface potential measurement
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This method enables precise surface potential measurement of semiconductor devices, unaffected by insulating film potentials, reducing manufacturing costs and improving image quality control in SEM inspection apparatus.
Implementation Method 1
The test object is irradiated with a primary electron beam, two S curves, that is, the dependency of secondary particle (for example, secondary electron or reflected electron) signal strength on sample charge control voltage, are observed
Data Source
AI summary
An inspection and measurement method and apparatus for semiconductor devices and patterns such as photomasks using an electron beam capable of measuring the potential of a sample with higher precision than conventional systems. When an S curve is observed in a semiconductor device to be inspected, fluctuations of the potential of the inspection sample surface are suppressed by optimizing the energy of a primary electron beam used for irradiation. When the surface potential of the semiconductor device is measured, a more precise measurement can be obtained without adverse effects from an insulation film surface. Further, the surface potential can be measured without installing a special apparatus for wafer surface potential measurement such as an energy filter, so the cost of the apparatus can be reduced.